Polyurethanes are materials of considerable utility in the production of rigid and flexible foams, solid and microcellular elastomers, sealants, coatings, and adhesives. The versatility, relatively low cost, and superior properties of polyurethanes have resulted in the rapid growth of the polyurethane industry over the past 50 years. Currently, many millions of pounds of polyurethanes are produced each year throughout the world. Unfortunately, most polyurethanes are thermoset materials which are cross-linked to one degree or another. Unlike thermoplastics such as polyethylene, polypropylene, and polystyrene, scrap or waste polyurethanes thus cannot be readily remelted or reprocessed into useful articles. Since it would be hi9highly desirable for economic and environmental reasons to reuse or recover the large volume of scrap or waste polyurethane generated each year rather than burning it or disposing of it in landfills, considerable inventive effort has been devoted to devising processes for recovering useful chemical components from scrap polyurethane materials.
Hydrolysis of a polyurethane using base catalysis so as to recover polyether polyols and polyamines is known in the art, but suffers from several disadvantages. At relatively low temperatures, the hydrolysis rate is slow. At higher temperatures, the rate is faster but certain undesired side reactions may occur. The amount of base (caustic}required is also high relative to the amount of polyurethane being treated, making the process economically unattractive.
The present invention overcomes the aforementioned deficiencies of prior art hydrolytic recovery methods by providing a process which accomplishes effective and selective hydrolysis of a polyurethane to active hydrogen-containing polyethers and polyamines using lower temperatures, lower levels of basic catalyst, and/or shorter treatment times.